Sub pulse length event measurement in BOTDR system using slope assisted Brillouin frequency shift

Area of Science:

• Physics
• Optical Engineering
• Materials Science

Background:

• Conventional Brillouin frequency shift (BFS) methods face limitations in measuring small event zones due to pulse width constraints.
• Accurate measurement of localized physical parameters in optical fibers is crucial for advanced sensing applications.

Purpose of the Study:

• To develop and validate a novel temperature demodulation scheme for measuring sub-pulse length event zones.
• To overcome the pulse width limitations inherent in traditional BFS-based measurement techniques.

Main Methods:

• Proposed a novel temperature demodulation scheme utilizing the slope-assisted Brillouin frequency shift (SA-BFS).
• Developed a theoretical model demonstrating a linear relationship between BFS slope and temperature.
• Validated the model through simulations and experiments with varying event zone lengths and pulse widths.

Main Results:

• Achieved a significant improvement in measurement capability, reducing the minimum measurable zone from 2 m to 0.49 m.
• Demonstrated precise temperature demodulation of 57.75 °C over a 10.2 km sensing fiber.
• Attained a temperature accuracy approximately ten times higher than conventional demodulation schemes.

Conclusions:

• The SA-BFS method offers a transformative approach for measuring physical quantities in distributed optical fiber sensing.
• This technique enhances the capability of distributed Brillouin scattering-based sensors like BOTDR and BOTDA.
• The proposed scheme enables precise characterization of sub-pulse length events, expanding the application scope of optical fiber sensors.